One of the most common complaints of patients in the ER is abdominal pain, and as a recent article at TIME.com details, diagnosis is rarely straightforward. It is important to understand that the ER is different from other places where healthcare is provided. ER physicians see a broad spectrum of disease – from the insignificant to the life-threatening. There are great time constraints in the ER, as well, and follow-up care is hard to arrange (and may be unreliable) so there is pressure for a definitive diagnosis in a single encounter.

Physicians considering the CT scan to assist with diagnosis for abdominal pain or other illness and injuries should consider three questions:

1.  Is CT the right test to do for this patient?

Many ER physicians are good at a answering this question, but it is also helpful to remember that the best expert on appropriate use is one phone call away: the radiologist. Having the patient’s EMR handy is important, too, in reporting how many CT scans this patient may have had historically, since this is a data-point in choosing whether or not to do CT. A national registry of individual patient cumulative radiation dose is coming to the U.S., similar to the one that now exists in the EEU, but it is not here yet.

2.  If CT is the right test, what kind of CT?

With contrast or without? Oral contrast or not? Positive oral contrast or negative? One pass or three? Arterial or portal venous phase? Abdomen only or abdomen plus pelvis? Again, the radiologist is a valuable consultant for getting the most information about the patient’s condition at the least radiation cost.

3.  How can the CT scan be done with the lowest possible radiation dose?

Finally, once the kind of CT exam is decided, how can it be done with the lowest possible radiation dose without compromising the diagnostic value of the scan. A well-informed radiologist can reduce the radiation dose per scan by up to 60 percent. For example, CT of the urinary tract with contrast now can be achieved in a single pass. Careful attention to CT imaging parameters can radically lower dose (low kVp, modulated mA, etc.). Limiting the length of the scan on the patient and careful centering of the patient by the tech can greatly reduce dose. In addition, newer scanners combine better detectors with more complex reconstruction algorithms to substantially lower dose and CT scan radiation risks.